1. Field of the Invention
The present invention relates to a fixing device which is employed in, e.g., a copying machine or printer apparatus using toner, and fixes a toner image onto a medium to be transferred.
2. Description of the Related Art
A fixing device which is assembled into a copying machine using an electrophotographic process heats and melts toner on a medium to be transferred, and fixes the toner onto the medium.
As a toner heating method usable in the fixing device, a method using radiation heat obtained by turning on a filament lamp, and a flash-fixing method using a flash lamp have widely been known. Recently, a fixing device using an induction heating device as a heat generation source is put into practical use.
In many cases, the fixing device uses a heat (fixing) roller which incorporates a heater, and a press roller which is pressed against the heat roller at one point on the outer surface of the heat roller at a predetermined pressure. With this structure, heat can be efficiently supplied from the heat generation source to toner. A pressure for fixing melted toner onto a medium to be transferred can be easily applied to the medium and toner.
Most of toners used in a copying machine and printer apparatus are granular particles or powder particles prepared by coating a pigment or dye with a hot-melt resin. Toner which is not fixed to a medium to be transferred often remains at a portion of the fixing device which contacts melted toner. Thus, many fixing devices having a cleaning device which recovers toner left on the heat roller are commercially available.
As a method of cleaning the heat roller, felt is brought into contact with the outer surface of the heat roller, and oil which prevents toner from attaching to the heat roller is supplied. Toner is fixed to a portion where it is brought into contact with the heat roller in the use of felt. Thus, the felt is formed into a roller shape to prevent toner from being fixed to one portion.
Even with the felt roller, the toner recoverable amount decreases and the image quality degrades during the maintenance cycle because of an increase in the image forming speed of a copying machine and printer apparatus and prolongation of the maintenance cycle of the copying machine and printer apparatus. If felt containing a large amount of toner is pressed against the heat roller for a long time, the heat roller surface is scratched.
To solve these problems, a web cleaning method of changing (shifting) the position of felt brought into contact with the heat roller in accordance with the cumulative image forming count (lapse of a predetermined time).
In the use of the felt web, the web containing toner is sequentially taken up. The replacement time of the cleaning device can be set by setting the web amount in accordance with the maintenance cycle. The web may be coated with oil which prevents toner from attaching to the heat roller.
Even if the felt web is adopted, the web amount assembled into the fixing device has an end portion (roll length) due to the maintenance cycle, the internal space of the apparatus, and the like.
If the web of the cleaning device runs out but image forming operation continues, the heat roller is quickly contaminated. In the worst case, the heat roller surface is scratched and cannot be used (must be replaced). Replacement of the heat roller requires a long time and high cost.
If the copying machine or printer apparatus is stopped when the web runs out, the serviceman mounts a new web, and the copying machine or printer apparatus can be used again without scratching the heat roller surface. However, the copying machine or printer apparatus cannot be used until the serviceman mounts a new web.
It is an object of the present invention to provide an image forming apparatus capable of operating a cleaning mechanism while preventing the stop of an image forming apparatus using a fixing device with the cleaning mechanism.
According to a first aspect of the present invention, there is provided a fixing device comprising: a heat-producing member which is formed into a hollow cylinder or an endless belt, has a outer surface of the cylinder or a belt surface of the belt movable at a predetermined speed, and can supply predetermined heat to a hot-melt substance and a medium holding the hot-melt substance; a pressure application mechanism which has a outer surface that can move following the outer surface of the cylinder or the belt surface of the belt when the outer surface of the cylinder or the belt surface of the belt of the heat-producing member is moved at the predetermined speed, and which applies a predetermined pressure to the heat-producing member while interposing the hot-melt substance and the medium between the heat-producing member and the pressure application mechanism; a heat-producing member exciter mechanism which is set to increase a temperature of the heat-producing member, and allows the object to generate heat; a hot-melt substance-taking member which is brought into contact with the outer surface of the cylinder or the belt surface of the belt of the heat-producing member at a predetermined pressure, and can take the hot-melt substance attached to the outer surface of the cylinder or the belt surface of the belt; a hot-melt substance-taking member changer which can move the hot-melt substance-taking member by a predetermined amount in a region where the hot-melt substance-taking member is brought into contact with the outer surface of the cylinder or the belt surface of the belt of the heat-producing member at the predetermined pressure when a predetermined amount of the hot-melt substance is absorbed in the hot-melt substance-taking member; a hot-melt substance-taking member changer control device which moves the hot-melt substance-taking member at a predetermined timing in the region where the hot-melt substance-taking member is brought into contact with the outer surface of the cylinder or the belt surface of the belt of the heat-producing member; and an end portion detection mechanism which can detect an end portion and a vicinity of the hot-melt substance-taking member, wherein, when the end portion detection mechanism detects that a remaining portion of the hot-melt substance-taking member reaches a predetermined amount up to the end portion of the hot-melt substance-taking member, an operation timing of the hot-melt substance-taking member changer by the hot-melt substance-taking member changer control device is delayed at a predetermined ratio.
According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a display which can display an operation state of the apparatus and a predetermined message; a photosensitive member which can hold an electrostatic image; a developing device which supplies toner to the electrostatic image formed on the photosensitive member and visualizes the electrostatic image; a transfer device which transfers, to a medium to be transferred, a toner image formed by supplying the toner from the developing device to the electrostatic image formed on the photosensitive member; and a fixing device which includes a heating member capable of supplying predetermined heat to the toner serving as the toner image on the medium to be transferred, a temperature increasing mechanism that increases temperatures of the heating member and a press member capable of applying a predetermined pressure to the heat member in order to fix the toner melted by heat from the heating member to the medium to be transferred, and a web cleaning mechanism that removes toner attached to a surface of the heating member, the fixing device applies heat and a pressure to the toner image transferred to the medium to be transferred, thereby fixing the toner image to the medium to be transferred, wherein the web cleaning mechanism includes a web which is brought into contact with the surface of the heating member, a web-taking mechanism which moves a web to which a predetermined amount of toner is attached upon contact with the surface of the heating member for a predetermined time, a remaining web amount detection mechanism which detects a remaining web amount, and a web-taking mechanism driver which operates the web-taking mechanism at a predetermined timing, and when the remaining web amount detection mechanism detects that the remaining web amount becomes not more than a predetermined amount, the display is instructed to display the predetermined message, and when the remaining web amount detection mechanism detects that the remaining web amount becomes not more than the predetermined amount, a timing at which the web-taking mechanism is operated by the web-taking mechanism driver can be reduced at a predetermined ratio.
According to a third aspect of the present invention, there is provided an image forming apparatus including a web cleaning mechanism as a heat roller cleaning mechanism, comprising: a detection mechanism which can detect absence of a web; a remaining amount detection mechanism which can detect a remaining amount of the web; a web feed amount control mechanism which changes a feed amount of the web in accordance with a condition; and a notifying mechanism which can output a warning that requests replacement of the web.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumetalities and combinations particularly pointed out hereinafter.